Tower crane with telescopic jib

ABSTRACT

This tower crane comprises a mast and a telescopic horizontally extending jib. Said jib is made of two lengths, i.e. a first length connected to the end of the mast and a second length of smaller cross section telescopically engaged through said first jib length. A rolling track for a trolley is provided in the lower portion of the first jib length. A further rolling track is arranged adjacent the free end of the second jib length, at the lower portion thereof, whereby in fully telescoped condition of the jib the rolling track provided on the second jib length form an extension of the rolling track pertaining to the first jib length. Latching means are provided for impeding undue movement of the trolley when the jib lengths are not in a fully telescoped condition.

United States Patent Pingon [54] TOWER CRANE WITH TELESCOPIC [72] Inventor: Pierre Joseph Pingon, 5 avenue du Parmelan, Annecy, France [22] Filed: Jan. 27, 1971 [2]] App], No.: 110,066

Related US. Application Data [62] Division of Ser. No. 846,792, Aug. 1, 1969,

Pat. No. 3,596,772.

[30] Foreign Application Priority Data Dec. 24, 1968 France ..68180317 Aug. 30.1968 France ..68164641 [52] US. Cl. ..212/56, 212/74, 212/102 [51] Int. Cl ..B66c 23/06 [58] Field of Search .212/56, 63, 73, 74, 75,15,

[56] References Cited UNITED STATES PATENTS 3,249,236 5/1966 Kummerman ..212/15 Aug. 29, 1972 3,006,485 10/1961 Martin ..l.212/74 Primary'ExaminerHarvey C. Homsby Att0mey-Young & Thompson 5 7 ABSTRACT This tower crane comprises a mast and a telescopic horizontally extending jib. Said jib is made of two lengths, i.e. a first length connected to the end of the mast and a second length of smaller cross section telescopically engaged through said first jib length. A rolling track for a trolley is provided in the lower portion of the first jib length. A further rolling track is arranged adjacent the free end of the second jib length, at the lower portion thereof, whereby in fully telescoped condition of the jib the rolling track provided on the second jib length form an extension of the rolling track pertaining to the first jib length. Latching means are provided for impeding undue movement of the trolley when the jib lengths are not in a fully telescoped condition.

4 Claims, 5 Drawing Figures PATENTEDwczs m2 sum 1 0r 2 Heme: JOSEPH P/A/e WV TOWER CRANE WITH TELESCOPIC .118 This application is a divisional application from Patent application Ser. No. 846,792, filed Aug. l, 1969 now US. Pat. No. 3,596,772.

BACKGROUND OF THE INVENTION The present invention relates generally to tower cranes and has more particular reference to tow cranes having a horizontal telescopic jib.

It is already known to provide telescopic jibs comprising a first jib length of closed cross section and a second jib length of smaller cross sectional area than the first jib length, and means for guiding the telescopic movement of said second jib length within said first jib length.

It has already been proposed to ensure guided movement of the second jib length within the first jib length through a first set of rollers arranged near the free end of the first jib length remote from the mast, and a second set of rollers provided near the inner end of the second jib length. In such a case, the first set of rollers is located near the lower portion of the first jib length, while the second set of rollers is located near the upper portion of the second jib length, so as to absorb the load strains supported by said second jib length.

However, in the known constructions, the load is carried by a lifting hook or similar means provided at the free end of the second jib length, whereby the jib or boom of the crane is angularly movable in a vertical plane to change its obliquity with respect to the horizontal.

One object of the invention is to provide a telescopic jib for a tower crane having a horizontal jib and a lifting or loading trolley movable along said jib.

Another object of the invention is to provide a telescopic horizontal jib whereby a trolley is movable on said jib from a first position located in the vicinity of the crane mast to a second position located at the free end of the horizontal jib.

According to the invention, the horizontal telescopic jib of the tower crane comprises a first jib length connected to said mast and a second jib length having a cross section smaller than the cross section of said first jib length and telescopically movable within said first jib length, whereby the first jib length has a pair of members providing a track on which the rollers of the crane trolley may roll and the second jib length carries adjacent its free end, which remains outside the first jib length in the fully telescoped condition of both jib lengths, elements providing a rolling track which, when the second jib length occupies its fully retracted or telescoped condition constitutes an extension of the rolling track provided on the first jib length.

In accordance with another feature of the invention, there is provided locking means adapted to hold the second jib length in a fully retracted position with respect to the first jib length as long as the trolley rests upon the latter, also means ensuring an unlocking action of said locking means when the trolley reaches the end of the second jib length. Another locking means holds the trolley upon the second jib length as long as the latter is partly disengaged from the first jib length and means control the unlocking action of said another locking means when the second jib length reaches a fully retracted position with respect to the first jib length. Such an arrangement permits the trolley and the telescoping action to be controlled from a single winch or the like. The transfer of said trolley from one jib length to the other is only possible in the full telescoped position, i.e. merely when the rolling track of the second jib length is abutted against the rolling track of the the first jib length, thereby providing a par ticularly safe assembly.

In order that the invention may be more easily understood and cam'ed into practice, it will be more fully described hereafter with reference to the accompanying non limitative drawings wherein:

FIGS. 1 and 2 are part diagrammatic views showing a horizontal telescopic crane jib according to the invention.

FIGS. 3, 4 and 5 are diagrammatic views showing the locking means in several operative positions.

Reference being first had to FIGS. 1 and 2, which only showthe jib of a tower crane the other parts of which can be identical to those visible in US. Pat. No. 3,596,772, said jib being hinged to the upper part of the mast of the tower crane, l designates the first stationary length or section of a horizontal telescopic crane jib and 2 designates the second (movable) jib length or section.

Said first length is sustained from the mast of the crane mast through a guy 3.

It will be seen from these two figures that the second jib length 2 has a cross sectional area smaller than that of the first jib length I. Said length 2 is guided by a first series of rollers 4 bearing on the lower face of the first jib length 1 adjacent its end, also on additional rollers 5 distributed throughout the length of said first jib length. The loading strain supported by the second jib length 2 is taken by a second series of rollers 6 provided at the foot end of the second jib length over its upper part, said rollers bearing upon the lower face of the upper part of the first jib length 1.

In the present case, the first jib length 1 is provided at its lower portion with a pair of members forming a rolling track 7 for the rollers 8 of the trolley 9. The second jib length 2 carries adjacent its free end, which remains outside the first jib length 1 itself in the fully telescoped position shown in dotted lines in FIG. 1, two chassis elements which together form a rolling track 10. When the second jib length 2 occupies a fully retracted or telescoped position, the track 10 forms a continuation of the rolling track 7 pertaining to the first jib length 1.

Reference being had to FIG. 1, it will be seen that the lifting cable 11 extending from the winch (not shown) is trained over a pulley 12 arranged at the head end of the mast, then over the pulleys of the trolley 9, over a jockey pulley l3 fitted at the free end of the second jib length 2 and over another jockey pulley 14 situated at the foot end of said second jib length, and is fastened at a point 15 adjacent the head end of the first jib length 1. This arrangement ensures, as telescoping action of the crane jib occurs, such a compensation of length that the lifting hook 16 may perform a horizontal motion.

In FIG. 2 is shown the arrangement adapted for the cable 17 that is used for controlling the trolley and for performing the telescoping action. The cable 17 which extends from the directing winch (not shown) is first trained over a pulley 18 provided at the head end of the mast and is secured to the trolley 9 at 19. Another cable run 20 extending from the securing point 19 is trained over a jockey pulley 24 provided at the free end of the second jib length 2 and then back inside the latter to a second jockey pulley 21 provided at its foot end, then over a horizontal jockey pulley 22 provided on the first jib length l and finally over a jockey pulley 23 provided at the foot end of said first jib length before reaching the directing winch. Owing to this arrangement, adequate control of the trolley motion over the first jib length is accomplished, also the telescoping action of the second jib length carrying the trolley at its end.

Reference will now be made to FIGS. 3 to which show the double locking device permitting control of the trolley and telescoping action from one and the same winch.

The second jib length 2 carries adjacent its end portion a hook 25 pivotally supported at 26 by said length and connected by a rod 27 with a lever 28 urged by a traction spring 29. In operative position, the beak of the hook 25 cooperates with a dog 30 provided on the first jib length 1 so as to interlock the two jib lengths in the fully telescoped position in which the two rolling tracks 7, form mutual extensions of each other. In this condition, the trolley 9 may pass over from one jib length to the other.

Such a device permits any separation of the two rolling tracks 7, 10 to be avoided as long as the trolley 9 is not on the second jib length 2. In order to ensure an unlocking action after the trolley has passed over the second jib length, said trolley carries an abutment 31 which engages the lever 28 (as shown in FIG. 4) so to move the hook off the dog as the trolley reaches the end of the second jib length. The latter may be then disengaged from the first jib length.

In order to hold the trolley 9 on the second jib length 2 as long as the latter has not been brought back to a fully telescoped condition i.e. as long as the rolling tracks 7,10 are not in abutted relation, there is provided on the second jib length a hook 33 pivotally supported at 34 and associated with a rod 35 cooperating with a compression spring 36 which normally holds the hook 33 in operative position, said rod terminating in an abutment 37. Another abutment 38 is provided on the first jib length. The trolley carries a hooking dog 39.

In the position shown in FIG. 5, it will be seen that the trolley is held on the second jib length 2 and is operatively connected therewith. When both jib lengths reach the fully telescoped position (as visible in FIG. 4) the abutments 37, 38 cooperate so as to control raising of the hook 33 which then frees the dog 39. The trolley can then be freely transferred onto the first jib length.

The entire movement takes place as follows. Assuming the trolley to be at the foot end of the jib, control of the directing winch forwardly acts through the cable run (FIG. 2) to cause the trolley to be moved forward to the end of the first jib length l, whereafter the trolley passes over the second (movable) jib length 2. When reaching its end, its abutment 31 hits the lever 28, thereby operating the hook 25 for freeing the jib length 2 which is then moved forwardly by the cable run situated between the two jib lengths as far as a fully extracted position is reached. During this movement, the lifting hook 16 of the crane effects a horizontal motion.

Reverse movement takes place in a similar fashion, namely reverse control of the directing winch performs, through the cable 17 (FIG. 2) rearward movement of the second jib length by the action of the hook 32. When this second jib length reaches the fully telescoped position, the abutments 38, 37 cooperate for operating the hook 33 and liberating the trolley 9 which then passes over the first jib length 1. During this movement, liberation of the lever 28 takes place, whereupon the two jib lengths l, 2 are interlocked. The trolley then continues its motion until the foot end of the jib is reached. Here again the movement of the lifting hook 16 is horizontal.

Minor constructional details may be varied without departing from the invention within the ambit of technical equivalencies.

What is claimed is:

l. A tower crane comprising a mast, a telescopic horizontally extending jib including a first length hinged to the end of the mast, a second length telescopically engaged through said first jib length, means for controlling the telescopic movement of the second jib length in said first jib length, members providing a rolling track in the lower portion of the first jib length, further members providing a rolling track arranged adjacent the end of the second jib length remote from the mast, adjacent the lower portion of said second jib length, in such positions that in fully telescoped condition of the jib, the members pertaining to said first and second jib lengths abut each other in end-to-end relationship but in extended condition of the jib said members are spaced apart from each other in the direction of their length, and a lifting trolley rolling on both said members of the two jib lengths only when said members are in said abutting relationship.

2. A tower crane according to claim 1, and locking device for holding the second jib length in fully retracted position in the first jib length as long as the trolley is on said first jib length, and means for unlatching said locking device when the trolley reaches said second jib length.

3. A tower crane according to claim 1 including a first locking device for holding the second jib length in fully retracted position in the first jib length when the trolley is situated on said first jib length, means for unlatching said first locking device when the trolley reaches said second jib length, a second locking device for holding the trolley upon the second jib length as long as the latter is partly disengaged from the first jib length, and means for controlling the unlatching of said second locking device when the second jib length reaches a fully telescoped position with respect to the first jib length.

4. A tower crane according to claim 1, including a first latching member pivotally mounted on said second jib length, asecond latching member provided on said first jib length, said first member being engaged with said second member when said second jib length is in a fully telescoped condition for locking said first and said second jib lengths in said fully telescoped condition, abutment means provided at the free end of said second jib length, means for operatively connecting said abutment means with said first latching member, so as to actuate said first latching member when said trolley is contacting said abutment means for unlocking said second jib length with respect to said first jib tuating means provided at the free end of said first jib 1 length, whereby said first and second actuating means are engaged with each other when said second jib length is in a fully telescoped condition so as to unlock said third latching member with respect to said fourth latching member and to enable for the transfer of the trolley from said second jib length to said first jib length in said fully telescoped condition of said second jib length. i 

1. A tower crane comprising a mast, a telescopic horizontally extending jib including a first length hinged to the end of the mast, a second length telescopically engaged through said first jib length, means for controlling the telescopic movement of the second jib length in said first jib length, members providing a rolling track in the lower portion of the first jib length, further members providing a rolling track arranged adjacent the end of the second jib length remote from the mast, adjacent the lower portion of said second jib length, in such positions that in fully telescoped condition of the jib, the members pertaining to said first and second jib lengths abut each other in end-toend relationship but in extended condition of the jib said members are spaced apart from each other in the direction of their length, and a lifting trolley rolling on both said members of the two jib lengths only when said members are in said abutting relationship.
 2. A tower crane according to claim 1, and locking device for holding the second jib length in fully retracted position in the first jib length as long as the trolley is on said first jib length, and means for unlatching said locking device when the trolley reaches said second jib length.
 3. A tower crane according to claim 1 including a first locking device for holding the second jib length in fully retracted position in the first jib length when the trolley is situated on said first jib length, means for unlatching said first locking device when the trolley reaches said second jib length, a second locking device for holding the trolley upon the second jib length as long as the latter is partly disengaged from the first jib length, and means for controlling the unlatching of said second locking device when the second jib length reaches a fully telescoped position with respect to the first jib length.
 4. A tower crane according to claim 1, including a first latching member pivotally mounted on said second jib length, a second latching member provided on said first jib length, said first member being engaged with said second member when said second jib length is in a fully telescoped condition for locking said first and said second jib lengths in said fully telescoped condition, abutment means provided at the free end of said second jib length, means for operatively connecting said abutment means with said first latching member, so as to actuate said first latching member when said trolley is contacting said abutment means for unlocking said second jib length with respect to said first jib length, a third latching member provided on said second jib length, a fourth latching member provided on said trolley, whereby said third and said fourth members are engaged with each other when said trolley rests on said second jib length so as to lock said trolley on said second jib length, first actuating means provided on said second jib length and operatively connected to said third latching member, and second actuating means provided at the free end of said first jib length, whereby said first and second actuating means are engaged with each other when said second jib length is in a fully telescoped condition so as to unlock said third latching member with respect to said fourth latching member and to enable for the transfer of the trolley from said second jib length to said first jib length in said fully telescoped condition of said second jib length. 